Volcanic Islands visited during the Voyage of the Beagle. 343 



not the first to notice — for many of them are matters of common and 

 daily observation — he has yet been the first to develope in the before 

 unsuspected greatness of their continual operation, and the first broad- 

 ly to exhibit as causes — as veroi causes — of geological phaenomena. 

 In his works, the agency of the winds, of the chemical elements dis- 

 solved in the waves which they impel, of the dust which they raise 

 and diffuse, of the depositions of rivers on the rocks over which they 

 flow, of the matter resulting from the action of the elements on col- 

 lections of animal excretions and exuviae, of the earth-worm as a la- 

 bourer in geological dynamics, of the compound-polyp which, sepa- 

 rating lime from sea- water, secretes its carbonate in the form of coral, 

 have been developed and portrayed for the first time in their ge- 

 nuine tenour and importance. With respect to coral reefs and islands, 

 much, indeed, had previously been effected, in part by English na- 

 turalists, in part by foreign voyagers ; but the true interpretation, we 

 conceive, of many of their observations, has been first given by Mr. 

 Darwin, together with numerous other facts which belong exclusively 

 to himself. 



In these geological observations on the volcanic islands visited du- 

 ring the voyage of the Beagle, we have the effects of both the qualities 

 of facile and accurate induction we have just attributed to their author. 

 Unlike some of his former works, they are not adapted to gratify the 

 general reader, or even to please the popular scientist, but they will 

 supply inestimable materials for the elucidation of volcanic geology, 

 in the hands of the profound investigator of nature, to whom they 

 will also be suggestive of some of the deepest questions of geological 

 causation. 



We have not before had a suitable opportunity of acknowledging 

 as it deserves the value of Mr. Darwin's contributions to science, and 

 were unwilling to omit such an acknowledgement when directing our 

 readers' attention to a work in which some of them are recorded. We 

 will now proceed to a brief analytical view of these "Observations," 

 and to extract from them certain portions, which we deem peculiarly 

 characteristic of their author's modes of thought and description. 



The title of the work states explicitly its contents. The first 

 130 pages relate almost exclusively to the volcanic islands and their 

 constitution, under the heads of St. Jago, in the Cape de Verde Ar- 

 chipelago, Fernando Noronha, Terceira, Tahiti, Mauritius, Ascension, 

 St. Helena, the Galapagos Archipelago, Trachyte and Basalt, Dis- 

 tribution of Volcanic Isles. The^ remainder of the volume consists of 

 observations chiefly on the geology of New South Wales, Van 

 Diemen's Land, New Zealand, King George's Sound, and the Cape 

 of Good Hope ; and an appendix contains descriptions of fossil 

 shells from a tertiary deposit at St. Jago, of extinct land-shells from 

 St. Helena, and of shells from the palaeozoic formation of Van Die- 

 men's Land, all by Mr. G. B. Sowerby ; together with descriptions 

 of fossil corals fi-om the same formation by Mr. Lonsdale, who, we 

 are thus happy to see, continues to aid the geologist by his valuable 

 labours in invertebral palaeontology. 



Of the manner in which the information imparted respecting these 



